Measurement of Thermal Diffusivity and Conductivity in Advanced Nanostructured Materials
- Author(s): Teweldebrhan, Desalegne Bekuretsion
- Advisor(s): Balandin, Alexander A
- et al.
Continuous device downscaling, growing integration densities of the nanoscale electronics and development of alternative information processing paradigms, such as spintronics, call for drastic increase in the data storage capacity. There is a strong need to engineer alternative materials, which can become foundation of new computational paradigms or lead to other applications such as efficient energy conversion. In this thesis I review results for the thermal and magnetic characterization of the near-field optical transducer for the heat-assisted magnetic recording for beyond the 10-Tbit/in2 densities. In order to record information, the heat-assisted magnetic recording system uses not only magnetic but also thermal energy. For this reason the recording media with the substantially higher anisotropy could be utilized to achieve the ultra-high recording densities. The heat-assisted magnetic recording and spintronic information processing require accurate thermal management of magnetic thin films. Here I report the results of the investigation of the thermal transport in Pd/CoPd/Pd magnetic multilayers with the thickness of individual layers in the nanometer range. Also, I investigate the thermal properties of FePt films when deposited on a Ag or Cu heat sink layer with varying thicknesses for the use in heat-assisted magnetic recording. It was found that the FePt films grown on Cu demonstrated the L10-FePt (001) texture while the FePt films grown on Ag appeared to be isotropic. As the thickness of the heat sink layer increased from 15 to 120 nm, the coercivity of the FePt films decreased from 1.7 - 1.5 Tesla for Cu, and 1.3 - 1.0 Tesla for Ag. Thermal conductivity measurements showed that as Ag and Cu thickness increased, the out-of-plane thermal conductivity decreased, demonstrating that the thermal conductivity can be adjusted by varying the heat sink layer.